Chip resistor and mounting structure thereof

ABSTRACT

A chip resistor with a reduced thickness is provided. The chip resistor includes an insulating substrate, a resistor embedded in the substrate, a first electrode electrically connected to the resistor, and a second electrode electrically connected to the resistor. The first electrode and the second electrode are spaced apart from each other in a lateral direction that is perpendicular to the thickness direction of the substrate.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a chip resistor and a mountingstructure of the chip resistor.

2. Description of the Related Art

Chip resistors have been widely used in various electronic apparatuses.JP 2007-142148A, for example, discloses a chip resistor that includes aresistive portion and two plate-shaped electrodes connected to theresistive portion.

With the conventional chip resistor, the plate-shaped electrodes need tohave a rather great thickness so that the chip resistor as a whole hasan appropriate strength. Due to this, the conventional chip resistor mayfail to have a desired small thickness. In addition, there has been astrong demand for improvement in heat dissipation performance of a chipresistor.

SUMMARY OF THE INVENTION

The present invention has been proposed in view of the foregoingcircumstances. It is therefore an object of the present invention toprovide a chip resistor that can be formed with a reduced thickness. Itis also an object of the present invention to provide a chip resistorwith improved heat dissipation performance.

According to a first aspect of the present invention, here is provided achip resistor that includes: an insulating substrate; a resistorembedded in the substrate; a first electrode electrically connected tothe resistor; and a second electrode electrically connected to theresistor. In the chip resistor, the first electrode is spaced apart fromthe second electrode in a first direction perpendicular to a thicknessdirection of the substrate.

According to a second aspect of the present invention, there is provideda chip resistor mounting structure that includes: a chip resistor inaccordance with the above-noted first aspect; a mounting substrate onwhich the chip resistor is mounted; and an electroconductive bondingportion disposed between the mounting substrate and the chip resistor.

Other features and advantages of the present invention will become moreapparent through the detailed description given below with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a mounting structure of a chipresistor according to a first embodiment of the present invention;

FIG. 2 is a partially seen-through plan view of the chip resistor, seenin the direction indicated by arrows II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along a line in FIGS. 1 and 2;

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIGS. 1 and2;

FIG. 5 is a partially seen-through plan view corresponding to FIG. 2,from which a first plated layer and a second plated layer are excluded;

FIG. 6 is a partially seen-through right side view of the chip resistorshown in FIG. 1;

FIG. 7 is a partially seen-through left side view of the chip resistorshown in FIG. 1;

FIG. 8 is a front view of the chip resistor shown in FIG. 1;

FIG. 9 is a rear view of the chip resistor shown in FIG. 1;

FIG. 10 is a plan view for explaining a manufacturing process of thechip resistor shown in FIG. 1;

FIG. 11 is a cross-sectional view taken along a line XI-XI in FIG. 10;

FIG. 12 is a rear view for explaining the manufacturing process thatfollows FIG. 10;

FIG. 13 is a cross-sectional view taken along a line XIII-XIII in FIG.12;

FIG. 14 is a rear view for explaining the manufacturing process thatfollows FIG. 12;

FIG. 15 is a cross-sectional view taken along a line XV-XV in FIG. 14;

FIG. 16 is a rear view for explaining the manufacturing process thatfollows FIG. 14:

FIG. 17 is a cross-sectional view taken along a line XVII-XVII in FIG.16;

FIG. 18 is a cross-sectional view showing a first variation of the firstembodiment;

FIG. 19 is a cross-sectional view showing a second variation of thefirst embodiment;

FIG. 20 is a cross-sectional view of a mounting structure of a chipresistor according to a second embodiment of the present invention;

FIG. 21 is a partially seen-through plan view of the chip resistor, seenin the direction indicated by arrows XXI-XXI in FIG. 20;

FIG. 22 is a cross-sectional view of the chip resistor taken along aline XXII-XXII in FIGS. 21 and 21;

FIG. 23 is a cross-sectional view of the chip resistor taken along aline XXIII-XXIII in FIGS. 20 and 21;

FIG. 24 is a partially seen-through plan view corresponding to FIG. 21,from which the first plated layer and the second plated layer areexcluded;

FIG. 25 is a partially seen-through right side view of the chip resistorshown in FIG. 20;

FIG. 26 is a partially seen-through left side view of the chip resistorshown in FIG. 20;

FIG. 27 is a front view of the chip resistor shown in FIG. 20;

FIG. 28 is a rear view of the chip resistor shown in FIG. 20;

FIG. 29 is a cross-sectional view for explaining a manufacturing processof the chip resistor shown in FIG. 20;

FIG. 30 is a plan view for explaining the manufacturing process thatfollows FIG. 29;

FIG. 31 is a cross-sectional view taken along a line XXXI-XXXI in FIG.30;

FIG. 32 is a rear view for explaining the manufacturing process thatfollows FIG. 30;

FIG. 33 is a cross-sectional view taken along a line XXXIII-XXXIII inFIG. 32;

FIG. 34 is a rear view for explaining the manufacturing process thatfollows FIG. 32;

FIG. 35 is a cross-sectional view taken along a line XXXV-XXXV in FIG.34;

FIG. 36 is a rear view for explaining the manufacturing process thatfollows FIG. 34;

FIG. 37 is a cross-sectional view taken along a line XXXVII-XXXVII inFIG. 36;

FIG. 38 is a cross-sectional view showing a first variation of thesecond embodiment;

FIG. 39 is a cross-sectional view showing a second variation of thesecond embodiment;

FIG. 40 is a cross-sectional view of a mounting structure of a chipresistor according to a third embodiment of the present invention;

FIG. 41 is a partially seen-through plan view of the chip resistor, seenin the direction indicated by arrows XLI-XLI in FIG. 40;

FIG. 42 is a plan view for explaining a manufacturing process of thechip resistor shown in FIG. 40;

FIG. 43 is a rear view for explaining the manufacturing process of thechip resistor shown in FIG. 40;

FIG. 44 is a cross-sectional view taken along a line XLIV-XLIV in FIGS.42 and 43;

FIG. 45 is a cross-sectional view for explaining the manufacturingprocess of the chip resistor shown in FIG. 40;

FIG. 46 is a cross-sectional view for explaining the manufacturingprocess that follows FIG. 45;

FIG. 47 is a cross-sectional view for explaining the manufacturingprocess that follows FIG. 46;

FIG. 48 is an enlarged fragmentary cross-sectional view of a firstconductive plate according to the third embodiment;

FIG. 49 is another enlarged fragmentary cross-sectional view of a firstconductive plate according to the third embodiment;

FIG. 50 is a cross-sectional view showing a chip resistor according to afirst variation of the third embodiment;

FIG. 51 is a cross-sectional view for explaining a manufacturing processof the chip resistor shown in FIG. 50;

FIG. 52 is a cross-sectional view for explaining the manufacturingprocess that follows FIG. 51; and

FIG. 53 is a cross-sectional view showing a chip resistor according to asecond variation of the third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

Referring to FIG. 1 through FIG. 19, a first embodiment of the presentinvention will be described. FIG. 1 is a cross-sectional view of themounting structure of a chip resistor according to the first embodimentof the present invention.

The chip resistor mounting structure 891 shown in FIG. 1 includes a chipresistor 100, a mounting substrate 893, and an electroconductive bondingportion 895.

The mounting substrate 893 is, for example, a printed circuit board. Themounting substrate 893 includes an insulating substrate and anon-illustrated pattern electrode formed on the insulating substrate.The insulating substrate is a glass epoxy resin substrate, for example.The chip resistor 100 is mounted on the mounting substrate 893. Thebonding portion 895, which is electroconductive as noted above, isdisposed between the chip resistor 100 and the mounting substrate 893.The bonding portion 895 serves to bond the chip resistor 100 and themounting substrate 893 together. The bonding portion 895 is, forexample, formed of solder.

FIG. 2 is a partially seen-through plan view of the chip resistor, seenin the direction indicated by arrows II-II in FIG. 1. FIG. 3 is across-sectional view taken along a line in FIGS. 1 and 2. FIG. 4 is across-sectional view taken along a line IV-IV in FIGS. 1 and 2. FIG. 5is a partially seen-through plan view corresponding to FIG. 2, fromwhich a first plated layer and a second plated layer are excluded. FIG.6 is a partially seen-through right side view of the chip resistor shownin FIG. 1. FIG. 7 is a partially seen-through left side view of the chipresistor shown in FIG. 1. FIG. 8 is a front view of the chip resistorshown in FIG. 1. FIG. 9 is a rear view of the chip resistor shown inFIG. 1.

The chip resistor 100 shown in the drawings above includes a substrate1, a resistor 2, a first electrode 4, a second electrode 5, and aninsulating layer 6.

The substrate 1 has a plate-like shape. The substrate 1 can be eitherinsulative or electroconductive. In the case where the substrate 1 is tobe made insulative, the material to form the substrate 1 may contain aresin or a ceramic. For the resin, use may be made of an epoxy resin toform the substrate 1. For the ceramic, use may be made of Al₂O₃, AlN, orSiC. In the case where the substrate 1 is to be made conductive, thesubstrate 1 may be formed of Cu or Ag, for example. In the illustratedembodiment, the substrate 1 is made of a glass epoxy resin.

The substrate 1 includes a substrate obverse surface 11, a substratereverse surface 12, a substrate first lateral face 13, a substratesecond lateral face 14, a substrate first end face 15, and a substratesecond end face 16.

The substrate obverse surface 11, the substrate reverse surface 12, thesubstrate first lateral face 13, the substrate second lateral face 14,the substrate first end face 15, and the substrate second end face 16are all flat. Referring to FIG. 1, the up-down direction in the figureis defined as the “thickness direction” Z1 of the substrate 1. In FIG.2, the “first direction” X1 runs to the right, and the “seconddirection” X2 runs to the left. Further, the “third direction” X3 runsupwards, and the “fourth direction” X4 runs downwards. The maximumthickness (maximum size in the thickness direction Z1) of the substrate1 is, for example, 60 to 300 μm. The thickness direction Z1 isperpendicular to each of the first direction X1, the second directionX2, the third direction X3 and the fourth direction X4. In addition,each of the first direction X1 and the second direction X2 isperpendicular to the third direction X3 and the fourth direction X4.

The size of the chip resistor 100 in the first direction X1 is, forexample, 5 to 10 mm, and the size of the chip resistor 100 in the thirddirection X3 is 2 to 10 mm for example.

The substrate obverse surface 11 and the substrate reverse surface 12are directed in the opposite directions to each other. In other words,the two surfaces 11, 12 are arranged to face away from each other. Thesubstrate first lateral face 13 is directed in the first direction X1,while the substrate second lateral face 14 is directed in the seconddirection X2. Thus, the substrate first lateral face 13 and thesubstrate second lateral face 14 are directed in opposite directions toeach other. The substrate first end face 15 is directed in the thirddirection X3, while the substrate second end face 16 is directed in thefourth direction X4. Thus, the substrate first end face 15 and thesubstrate second end face 16 are directed in opposite directions to eachother.

In this embodiment, the substrate 1 is a glass epoxy resin substrate asstated above. Hence, the substrate 1 includes a glass fiber portion 191and a resin portion 192. The resin portion 192 defines the outer profileof the substrate 1. The resin portion 192 is formed of an epoxy resin,for example. The resin portion 192 constitutes the substrate obversesurface 11 and the substrate reverse surface 12.

The glass fiber portion 191 is formed of glass fiber. Specifically, theglass fiber portion 191 is formed by stacking glass fiber cloths. Theglass fiber portion 191 constitutes a part of the substrate firstlateral face 13, a part of the substrate second lateral face 14, a partof the substrate first end face 15, and a part of the substrate secondend face 16.

According to the present invention, the substrate 1 may not be made of aglass epoxy resin. In that case, the substrate 1 may not include anyglass fiber portion.

As shown in FIG. 1, the resistor 2 is disposed in the substrate 1.Specifically, the resistor 2 is located on the side of the substrateobverse surface 11 of the substrate 1. The thickness (size in thethickness direction Z1) of the resistor 2 is, for example, 50 to 200 μm.In this embodiment, the resistor 2 has a serpentine shape when viewed inthe thickness direction Z1. Forming the resistor 2 in the serpentineshape is preferable e.g. for increasing the resistance of the resistor2. The resistor 2 may have a strip-like shape extending in the firstdirection X1 instead of the serpentine shape as in this embodiment. Theresistor 2 is formed of a resistive metal material, the examples ofwhich include manganin, zeranin, a Ni—Cr alloy, a Cu—Ni alloy, and aFe—Cr alloy.

As shown in FIGS. 1 and 3, the resistor 2 includes a resistor obversesurface 21, a resistor reverse surface 22, a resistor first lateral face23, and a resistor second lateral face 24. The resistor obverse surface21, the resistor reverse surface 22, the resistor first lateral face 23,and the resistor second lateral face 24 are all flat. The resistorobverse surface 21 and the resistor reverse surface 22 are directed inopposite directions to each other. The resistor obverse surface 21 isdirected in the same direction as the direction in which the substrateobverse surface 11 is directed, i.e., downward in FIG. 1. The resistorreverse surface 22 is directed in the same direction as the direction inwhich the substrate reverse surface 12 is directed, i.e., upward inFIG. 1. The resistor reverse surface 22 is directed to the substrate 1.The resistor first lateral face 23 is directed in the first directionX1. In this embodiment, the resistor first lateral face 23 is flush withthe substrate first lateral face 13. The resistor second lateral face 24is directed in the second direction X2. In this embodiment, the resistorsecond lateral face 24 is flush with the substrate second lateral face14.

In this embodiment, the resistor 2 is embedded in the substrate 1. To bemore detailed, the chip resistor 100 is configured as described below.

On the side of the substrate obverse surface 11, the resistor 2 isrecessed into the substrate 1 in a direction from the substrate obversesurface 11 toward the substrate reverse surface 12, so that the entiretyof the resistor 2 overlaps the substrate 1 in the thickness direction Z1(in other words, overlaps the substrate when viewed in a directionperpendicular to the thickness direction Z1). The resistor 2 is indirect contact with the substrate 1. Further, in this embodiment inwhich the substrate 1 is made of glass epoxy resin, the resistor 2 is indirect contact with the glass fiber portion 191 of the substrate 1.

The resistor obverse surface 21 is flush with the substrate obversesurface 11 of the substrate 1. This configuration is advantageous toforming the insulating layer 6 on the resistor obverse surface 21 andthe substrate obverse surface 11, as will be described later. Theresistor reverse surface 22 is in direct contact with the substrate 1.Further, in this embodiment in which the substrate 1 is the glass epoxyresin substrate, the resistor reverse surface 22 is in direct contactwith the glass fiber portion 191 of the substrate 1.

According to the present invention, the resistor 2 and the substrate 1may not be in direct contact with each other as in this embodiment. Forexample, the resistor 2 may be embedded in the substrate 1 with abonding layer disposed therebetween. Also, the resistor 2 may not be indirect contact with the glass fiber portion 191.

The insulating layer 6 is formed so as to cover the resistor 2. Theinsulating layer 6 is in direct contact with the resistor 2 and thesubstrate 1. The insulating layer 6 is in direct contact with theresistor obverse surface 21 of the resistor 2 and the substrate obversesurface 11 of the substrate 1. The resistor 2 includes portions that arespaced apart from each other in the first direction X1 (or the seconddirection X2, for that matter), and that are left uncovered by theinsulating layer 6. The insulating layer 6 is, for example, formed of athermosetting material. The size of the insulating layer 6 in the X3-X4direction is equal to the size of the substrate 1 in the X3-X4direction. The maximum thickness (maximum size in the thicknessdirection Z1) of the insulating layer 6 is, for example, 20 to 60 μm.The insulating layer 6 is formed of a resin, for example. It ispreferable to employ a material having high heat conductance to form theinsulating layer 6, in order to facilitate heat generated in theresistor 2 to be dissipated to outside of the chip resistor 100. It ispreferable that the heat conductance of the insulating layer 6 is higherthan that of the material constituting the substrate 1 (in thisembodiment, material constituting the resin portion 192). Preferably,the heat conductance of the insulating layer 6 is 1.0 W/(m·K) to 5.0W/(m·K).

The insulating layer 6 includes an insulating layer obverse surface 61,an insulating layer reverse surface 62, an insulating layer firstlateral face 63, an insulating layer second lateral face 64, aninsulating layer first end face 65, and an insulating layer second endface 66.

The insulating layer obverse surface 61 and the insulating layer reversesurface 62 are directed in opposite directions to each other. Theinsulating layer obverse surface 61 is directed in the same direction asthe direction in which the resistor obverse surface 21 is directed,i.e., downward in FIG. 1. The first electrode 4 and the second electrode5 are provided on the insulating layer obverse surface 61. A part of theinsulating layer obverse surface 61, more specifically a region of theinsulating layer obverse surface 61 between the first electrode 4 andthe second electrode 5, is exposed from the first electrode 4 and thesecond electrode 5. The insulating layer reverse surface 62 is directedin the same direction as the direction in which the resistor reversesurface 22 is directed, i.e., upward in FIG. 1. In this embodiment, theinsulating layer reverse surface 62 is in direct contact with theresistor 2 and the substrate 1. Specifically, the insulating layerreverse surface 62 is in direct contact with the resistor obversesurface 21 and the substrate obverse surface 11. The insulating layerfirst lateral face 63 is directed in the first direction X1. Theinsulating layer second lateral face 64 is directed in the seconddirection X2. The insulating layer first end face 65 is directed in thethird direction X3. In this embodiment, the insulating layer first endface 65 is flush with the substrate first end face 15. The insulatinglayer second end face 66 is directed in the fourth direction X4. Theinsulating layer second end face 66 is flush with the substrate secondend face 16.

The first electrode 4 is electrically connected to the resistor 2. Thefirst electrode 4 serves to supply power to the resistor 2 from themounting substrate 893 on which the chip resistor 100 is mounted. Thefirst electrode 4 is in direct contact with the resistor 2. In thisembodiment, the first electrode 4 is in direct contact with the resistorobverse surface 21 of the resistor 2. In this embodiment, further, thefirst electrode 4 is formed so as to cover the resistor first lateralface 23 of the resistor 2 and the insulating layer 6. In thisembodiment, the insulating layer 6 is disposed between the firstelectrode 4 and the resistor 2. In this embodiment, still further, thefirst electrode 4 is not formed so as to cover the substrate reversesurface 12. However, the first electrode 4 may be formed so as to coverthe substrate reverse surface 12, unlike in this embodiment. In themounting structure 891, as shown in FIG. 1, the first electrode 4 is indirect contact with the bonding portion 895, to be electricallyconnected to a non-illustrated interconnect pattern formed on themounting substrate 893, through the bonding portion 895.

The first electrode 4 includes a first underlying layer 41 and a firstplated layer 43.

The first underlying layer 41 is in direct contact with the resistor 2.In this embodiment, the first underlying layer 41 serves as the base forforming the first plated layer 43 on the insulating layer 6 by a platingmethod. The first underlying layer 41 is in direct contact with theportion of the resistor obverse surface 21 exposed from the insulatinglayer 6. The first underlying layer 41 is formed so as to overlap theresistor 2 when viewed in the thickness direction Z1 of the substrate 1.In addition, the first underlying layer 41 includes a portion separatedfrom the resistor 2 in the thickness direction Z1. The insulating layer6 is disposed between the first underlying layer 41 and the resistor 2.The first underlying layer 41 is disposed between the first plated layer43 and the insulating layer 6. In this embodiment, it is preferable thatthe first underlying layer 41 has a large size in the first directionX1. Preferably, for example, the size of the first underlying layer 41in the first direction X1 is equal to or larger than a quarter of thesize of the resistor 2 in the first direction X1, and more preferably,equal to or larger than one third of the size of the resistor 2 in thefirst direction X1. The size of the first underlying layer 41 in thefirst direction X1 is, for example, 600 to 3200 μm. The first underlyinglayer 41 is thinner than the resistor 2. The first underlying layer 41may be formed by physical vapor deposition (PVD), chemical vapordeposition (CVD), or printing. In this embodiment, the first underlyinglayer 41 is formed by sputtering. The thickness of the first underlyinglayer 41 is, for example, 100 to 500 nm. The first underlying layer 41may contain Ni and Cr, for example.

The first underlying layer 41 includes an underlying layer first lateralface 413. The underlying layer first lateral face 413 is directed in thefirst direction X1. In this embodiment, the underlying layer firstlateral face 413 is flush with the substrate first lateral face 13 andthe resistor first lateral face 23.

The first plated layer 43 is formed so as to directly cover the firstunderlying layer 41. The first plated layer 43 is provided on theresistor 2, and is in direct contact with the insulating layer 6. Thefirst plated layer 43 is in direct contact with a portion of theinsulating layer 6 that is offset in the direction X2 from the firstunderlying layer 41. In the chip resistor 100 not mounted yet on themounting substrate 893, the first plated layer 43 is outwardly exposed.Therefore, as shown in FIG. 1, in the mounting structure 891 the firstplated layer 43 is in direct contact with the bonding portion 895, thusto be electrically connected to the non-illustrated interconnect patternformed on the mounting substrate 893, through the bonding portion 895.In this embodiment, further, the first plated layer 43 is formed so asto cover the resistor first lateral face 23 of the resistor 2. Such aconfiguration is preferable because of allowing a solder fillet to beformed on the bonding portion 895.

More specifically, in this embodiment the first plated layer 43 includesa Cu layer 43 a, a Ni layer 43 b, and a Sn layer 43 c. The Cu layer 43 ais formed so as to directly cover the first underlying layer 41. The Nilayer 43 b directly covers the Cu layer 43 a. The Sn layer 43 c directlycovers the Ni layer 43 b, and is outwardly exposed. In the mountingstructure 891 of the chip resistor 100, the bonding portion 895 (in thisembodiment, solder) is bonded onto the Sn layer 43 c. For example, theCu layer 43 a has a thickness of 10 to 50 μm, the Ni layer 43 b has athickness of 1 to 10 μm, and the Sn layer 43 c has a thickness of 1 to10 μm. According to the present invention, the first plated layer 43 maynot include the Ni layer 43 b as in this embodiment.

The second electrode 5 is offset in the direction X2 from the firstelectrode 4. The second electrode 5 is electrically connected to theresistor 2. The second electrode 5 serves to supply power to theresistor 2 from the mounting substrate 893 on which the chip resistor100 is mounted. The second electrode 5 is in direct contact with theresistor 2. In this embodiment, the second electrode 5 is in directcontact with the resistor obverse surface 21 of the resistor 2. In thisembodiment, further, the second electrode 5 is formed so as to cover theresistor second lateral face 24 of the resistor 2 and the insulatinglayer 6. In this embodiment, the insulating layer 6 is disposed betweenthe second electrode 5 and the resistor 2. In this embodiment, stillfurther, the second electrode 5 is not formed so as to cover thesubstrate reverse surface 12. However, the second electrode 5 may beformed so as to cover the substrate reverse surface 12, unlike in thisembodiment. In the mounting structure 891, as shown in FIG. 1, thesecond electrode 5 is in direct contact with the bonding portion 895,thus to be electrically connected to the non-illustrated interconnectpattern formed on the mounting substrate 893, through the bondingportion 895.

The second electrode 5 includes a second underlying layer 51 and asecond plated layer 53.

The second underlying layer 51 is in direct contact with the resistor 2.In this embodiment, the second underlying layer 51 serves as the basefor forming the second plated layer 53 on the insulating layer 6 by aplating method. The second underlying layer 51 is in direct contact withthe portion of the resistor obverse surface 21 exposed from theinsulating layer 6. The insulating layer 6 is disposed between thesecond underlying layer 51 and the resistor 2. The second underlyinglayer 51 is disposed between the second plated layer 53 and theinsulating layer 6. In this embodiment, it is preferable that the secondunderlying layer 51 has a large size in the first direction X1 (or thesecond direction X2). Preferably, for example, the size of the secondunderlying layer 51 in the first direction X1 is equal to or larger thana quarter of the size of the resistor 2 in the first direction X1, andmore preferably, equal to or larger than one third of the size of theresistor 2 in the first direction X1. The size of the second underlyinglayer 51 in the first direction X1 is, for example, 600 to 3200 μm. Thesecond underlying layer 51 is thinner than the resistor 2. The secondunderlying layer 51 may be formed by PVD, CVD, or printing. In thisembodiment, the second underlying layer 51 is formed by sputtering. Thethickness of the second underlying layer 51 is, for example, 100 to 500nm. The second underlying layer 51 may contain Ni and Cr, for example.

The second underlying layer 51 includes an underlying layer secondlateral face 514. The underlying layer second lateral face 514 isdirected in the second direction X2. In this embodiment, the underlyinglayer second lateral face 514 is flush with the substrate second lateralface 14 and the resistor second lateral face 24.

The second plated layer 53 is formed so as to directly cover the secondunderlying layer 51. The second plated layer 53 is provided on theresistor 2, and is in direct contact with the insulating layer 6. Thesecond plated layer 53 is in direct contact with a portion of theinsulating layer 6 located on the X1-side with respect to the secondunderlying layer 51. In the chip resistor 100 not mounted yet on themounting substrate 893, the second plated layer 53 is outwardly exposed.Therefore, as shown in FIG. 1, in the mounting structure 891 the secondplated layer 53 is in direct contact with the bonding portion 895, thusto be electrically connected to the non-illustrated interconnect patternformed on the mounting substrate 893, through the bonding portion 895.In this embodiment, further, the second plated layer 53 is formed so asto cover the resistor second lateral face 24 of the resistor 2. Such aconfiguration is preferable because of allowing a solder fillet to beformed on the bonding portion 895.

More specifically, in this embodiment the second plated layer 53includes a Cu layer 53 a, a Ni layer 53 b, and a Sn layer 53 c. The Culayer 53 a is formed so as to directly cover the second underlying layer51. The Ni layer 53 b directly covers the Cu layer 53 a. The Sn layer 53c directly covers the Ni layer 53 b, and is outwardly exposed. In themounting structure 891 of the chip resistor 100, the bonding portion 895(in this embodiment, solder) is bonded onto the Sn layer 53 c. Forexample, the Cu layer 53 a has a thickness of 10 to 50 μm, the Ni layer53 b has a thickness of 1 to 10 μm, and the Sn layer 53 c has athickness of 1 to 10 μm. According to the present invention, the secondplated layer 53 may not include the Ni layer 53 b as in this embodiment

A manufacturing method of the chip resistor 100 will be described below.

Referring to FIGS. 10 and 11, a composite sheet 850 is first prepared.The composite sheet 850 is composed of a substrate sheet 810 and aresistor block 820. In this embodiment, the resistor block 820 isembedded in the substrate sheet 810 in the composite sheet 850. Thecomposite sheet 850 is formed, for example, by vacuum pressing. In thecomposite sheet 850, the resistor block 820 is firmly fixed to thesubstrate sheet 810.

The substrate sheet 810 is the material to be formed into the substrate1. The resistor block 820 is the material to be formed into the resistor2. Accordingly, the resistor block 820 is in direct contact with theglass fiber portion 191, in the composite sheet 850.

The resistor block 820 is composed of a plurality of sections, each ofwhich is to be formed into the resistor 2. In this embodiment, aplurality of serpentine-shaped sections are formed in advance by etchingor punching in the resistor block 820, to form the serpentine-shapedresistor 2.

Then the resistance of the resistor 2 in the resistor block 820 isadjusted. The adjustment of the resistance of the resistor 2 isperformed, for example, by grinding the resistor block 820.

Proceeding to FIGS. 12 and 13, an insulating film 860 is formed. Theinsulating film 860 is the material to be formed into the insulatinglayer 6. The insulating film 860 is formed as a plurality of stripsextending in one direction, for example by printing or application. Apart of the resistor block 820 is exposed from the insulating film 860.

Proceeding to FIGS. 14 and 15, a conductive material 840 is formed onthe resistor block 820. The conductive material 840 is to be formed intothe first underlying layer 41 or the second underlying layer 51. Thedeposition of the conductive material 840 may be performed through a PVDor CVD process. In the case of forming the conductive material 840 byPVD, for example sputtering may be performed. In this embodiment, theconductive material 840 is formed in a strip shape along the insulatingfilm 860, and therefore a part of the insulating film 860 is exposedfrom the conductive material 840. To form the conductive material 840 ina strip shape, for example a masking method may be adopted. Theconductive material 840 may be formed of Ni or Cr, for example.

As shown in FIGS. 16 and 17, the resistor block 820 is cut into aplurality of individual pieces 886. In this embodiment, the compositesheet 850 (resistor block 820 and substrate sheet 810) is collectivelycut. To obtain the individual pieces 886, for example a punching ordicing method may be adopted. In this embodiment, punching is performedto obtain the individual pieces 886.

The cutting process to obtain the individual pieces 886 provides thesubstrate first lateral face 13, the substrate second lateral face 14,the substrate first end face 15, the substrate second end face 16, theresistor first lateral face 23, the resistor second lateral face 24, theunderlying layer first lateral face 413, the underlying layer secondlateral face 514, the insulating layer first end face 65, and theinsulating layer second end face 66. By cutting the substrate sheet 810and the resistor block 820 at a time, the substrate first lateral face13, the resistor first lateral face 23, and the underlying layer firstlateral face 413 can be made flush with each other. Likewise, cuttingthe substrate sheet 810 and the resistor block 820 at a time makes thesubstrate second lateral face 14, the resistor second lateral face 24,and the underlying layer second lateral face 514 flush with each other.Likewise, the above cutting process makes the substrate first end face15 and the insulating layer first end face 65 flush with each other.Further, the above cutting process makes the substrate second end face16 and the insulating layer second end face 66 flush with each other.

Then the first plated layer 43 (Cu layer 43 a, Ni layer 43 b, and Snlayer 43 c) and the second plated layer 53 (Cu layer 53 a, Ni layer 53b, and Sn layer 53 c) shown in FIG. 1 are formed on each of theindividual pieces 886. To form the first plated layer 43 and the secondplated layer 53, for example a barrel plating method may be employed.Throughout the foregoing process, the chip resistor 100 can be obtained.

This embodiment provides the following advantages, for example.

In this embodiment, the resistor 2 is embedded in the substrate 1. Sucha configuration ensures that the overall size of the substrate 1 and theresistor 2 in the thickness direction Z1 of the substrate 1 are to bereduced. Therefore, the chip resistor 100 can be formed in a reducedthickness.

To manufacture the chip resistor 100, the composite sheet 850 formed ofthe substrate sheet 810 in which the resistor block 820 is embedded canbe employed. Therefore, it suffices to prepare the composite sheet 850in order to manufacture the chip resistor 100, and the step of adheringthe resistor block 820 onto the substrate sheet 810 can be excluded. Asa result, the production efficiency of the chip resistor 100 can beimproved.

In this embodiment, the insulating layer 6 has a heat conductance ashigh as 1.0 W/(m·K) to 5.0 W/(m·K). Such a property facilitates the heatgenerated in the resistor 2 to be dissipated to outside of the chipresistor 100 through the insulating layer 6. Therefore, the chipresistor 100 can be prevented from being overheated.

In this embodiment, the first electrode 4 includes the first underlyinglayer 41 in direct contact with the resistor 2 and the first platedlayer 43 covering the first underlying layer 41. The insulating layer 6is disposed between the first underlying layer 41 and the resistor 2.The mentioned configuration facilitates the first plated layer 43 to beformed on the insulating layer 6. Therefore, the first electrode 4 canbe formed with a larger area. The increase in area of the firstelectrode 4 facilitates the heat generated in the resistor 2 to bedischarged to the mounting substrate 893 through the first electrode 4.Thus, the heat dissipation performance of the chip resistor 100 can beimproved.

In this embodiment, the substrate 1 is formed of an insulative material.In this case, there is no need to employ a Cu electrode which isrelatively thick. Accordingly, the step of processing the Cu electrodecan be skipped, and resultantly the production efficiency of the chipresistor 100 can be improved.

In this embodiment, the substrate 1 and the mounting substrate 893 areboth glass epoxy resin substrates. Accordingly, the substrate 1 and themounting substrate 893 have generally the same thermal expansioncoefficient. When the substrate 1 is thermally expanded during the useof the chip resistor 100, the mounting substrate 893 is supposed tothermally expand at the same rate. Such a configuration prevents amalfunction that may arise from the impact of thermal expansion duringthe use of the chip resistor 100, for example fracture of the chipresistor 100.

First Variation of First Embodiment

Referring to FIG. 18, a first variation of the first embodiment of thepresent invention will be described.

FIG. 18 is a cross-sectional view showing the first variation of thefirst embodiment.

A chip resistor 101 shown in FIG. 18 is different from the chip resistor100 in that the resistor first lateral face 23 and the resistor secondlateral face 24 of the resistor 2 are covered with the substrate 1. Theremaining portions are configured in the same way as those of the chipresistor 100, and hence the description will not be repeated.

The chip resistor 101 can also provide the same advantages as thoseprovided by the chip resistor 100.

Referring to FIG. 19, a second variation of the first embodiment of thepresent invention will be described.

FIG. 19 is a cross-sectional view showing the second variation of thefirst embodiment.

A chip resistor 102 shown in FIG. 19 is different from the chip resistor100 in that the first plated layer 43 includes a face that is flush withthe underlying layer first lateral face 413 of the first underlyinglayer 41, and that the second plated layer 53 includes a face that isflush with the underlying layer first lateral face 514 of the secondunderlying layer 51. The remaining portions are configured in the sameway as those of the chip resistor 100, and hence the description willnot be repeated. Here, to manufacture the chip resistor 102, the platedlayer is formed in advance of the cutting process of the composite sheet850 described with reference to FIGS. 16 and 17.

The chip resistor 102 can also provide the same advantages as thoseprovided by the chip resistor 100.

Referring now to FIG. 20 through FIG. 39, a second embodiment of thepresent invention will be described.

FIG. 20 is a cross-sectional view of a mounting structure of a chipresistor according to the second embodiment of the present invention.

A chip resistor mounting structure 892 shown in FIG. 20 includes a chipresistor 200, the mounting substrate 893, and the bonding portion 895.

The mounting substrate 893 and the bonding portion 895 are configured inthe same way as those of the first embodiment, and hence the descriptionwill not be repeated in this embodiment.

FIG. 21 is a partially seen-through plan view of the chip resistor, seenin the direction indicated by arrows XXI-XXI in FIG. 20. FIG. 22 is across-sectional view of the chip resistor taken along a line XXII-XXIIin FIGS. 21 and 21. FIG. 23 is a cross-sectional view of the chipresistor taken along a line XXIII-XXIII in FIGS. 20 and 21. FIG. 24 is apartially seen-through plan view corresponding to FIG. 21, from whichthe first plated layer and the second plated layer are excluded. FIG. 25is a partially seen-through right side view of the chip resistor shownin FIG. 20. FIG. 26 is a partially seen-through left side view of thechip resistor shown in FIG. 20. FIG. 27 is a front view of the chipresistor shown in FIG. 20. FIG. 28 is a rear view of the chip resistorshown in FIG. 20.

The chip resistor 200 shown in the drawings above includes the substrate1, the resistor 2, a bonding layer 3, the first electrode 4, the secondelectrode 5, and the insulating layer 6.

The substrate 1 has a plate-like shape. The substrate 1 may be eitherinsulative or conductive. In the case where the substrate 1 is to bemade insulative, the material to form the substrate 1 may contain aresin or a ceramic. For example, an epoxy resin may be employed to formthe substrate 1. Regarding the ceramic, for example Al₂O₃, AlN, and SiCmay be employed. In the case where the substrate 1 is to be madeconductive, the substrate 1 may be formed of Cu or Ag, for example. Inthe illustrated embodiment, the substrate 1 is a glass epoxy resinsubstrate.

The substrate 1 includes the substrate obverse surface 11, the substratereverse surface 12, the substrate first lateral face 13, the substratesecond lateral face 14, the substrate first end face 15, and thesubstrate second end face 16.

The substrate obverse surface 11, the substrate reverse surface 12, thesubstrate first lateral face 13, the substrate second lateral face 14,the substrate first end face 15, and the substrate second end face 16are all flat. Referring to FIG. 20, the up-down direction in the figureis defined as the “thickness direction” Z1 of the substrate 1. In FIG.21, the “first direction” X1 runs to the right, and the “seconddirection” X2 runs to the left. Further, the “third direction” X3 runsupwards, and the “fourth direction” X4 runs downwards. The maximumthickness (maximum size in the thickness direction Z1) of the substrate1 is, for example, 60 to 300 μm. The thickness direction Z1 isperpendicular to each of the first direction X1, the second directionX2, the third direction X3 and the fourth direction X4. In addition,each of the first direction X1 and the second direction X2 isperpendicular to the third direction X3 and the fourth direction X4.

The size of the chip resistor 200 in the first direction X1 is, forexample, 5 to 10 mm, and the size of the chip resistor 200 in the thirddirection X3 is 2 to 10 mm for example.

The substrate obverse surface 11 and the substrate reverse surface 12are directed in opposite directions to each other. The substrate firstlateral face 13 is directed in the first direction X1. The substratesecond lateral face 14 is directed in the second direction X2. Thus, thesubstrate first lateral face 13 and the substrate second lateral face 14are directed in opposite directions to each other. The substrate firstend face 15 is directed in the third direction X3. The substrate secondend face 16 is directed in the fourth direction X4. In other words, thesubstrate first end face 15 and the substrate second end face 16 aredirected in opposite directions to each other.

As shown in FIG. 20, the resistor 2 is disposed in the substrate 1.Specifically, the resistor 2 is located on a side of the substrateobverse surface 11 of the substrate 1. The thickness (size in thethickness direction Z1) of the resistor 2 is, for example, 50 to 200 μm.In this embodiment, the resistor 2 has a serpentine shape when viewed inthe thickness direction Z1. Forming the resistor 2 in the serpentineshape is preferable e.g. for increasing the resistance of the resistor2. The resistor 2 may have a strip-like shape extending in the firstdirection X1 instead of the serpentine shape as in this embodiment. Theresistor 2 is formed of a resistive metal material, the examples ofwhich include manganin, zeranin, a Ni—Cr alloy, a Cu—Ni alloy, and aFe—Cr alloy.

As shown in FIGS. 21 and 22, the resistor 2 includes the resistorobverse surface 21, the resistor reverse surface 22, the resistor firstlateral face 23, and the resistor second lateral face 24. The resistorobverse surface 21, the resistor reverse surface 22, the resistor firstlateral face 23, and the resistor second lateral face 24 are all flat.

The resistor obverse surface 21 and the resistor reverse surface 22 aredirected in opposite directions to each other. The resistor obversesurface 21 is directed in the same direction as the direction in whichthe substrate obverse surface 11 is directed, i.e., downward in FIG. 20.The resistor reverse surface 22 is directed in the same direction as thedirection in which the substrate reverse surface 12 is directed, i.e.,upward in FIG. 20. The resistor reverse surface 22 is directed to thesubstrate 1. The resistor first lateral face 23 is directed in the firstdirection X1. In this embodiment, the resistor first lateral face 23 isflush with the substrate first lateral face 13. The resistor secondlateral face 24 is directed in the second direction X2. In thisembodiment, the resistor second lateral face 24 is flush with thesubstrate second lateral face 14.

The bonding layer 3 is disposed between the substrate 1 and the resistor2. Specifically, the bonding layer 3 is disposed between the substrateobverse surface 11 of the substrate 1 and the resistor 2. The bondinglayer 3 serves to bond the resistor 2 and the substrate obverse surface11 together. It is preferable that the bonding layer 3 is formed of aninsulative material, typically an epoxy-based material. The thickness(size in the thickness direction Z1) of the bonding layer 3 is, forexample, 30 to 100 μm. As shown in FIGS. 21 and 22, the bonding layer 3covers the entirety of the substrate obverse surface 11 in thisembodiment.

The bonding layer 3 may be provided only on a part of the substrateobverse surface 11, unlike in this embodiment. For example, the bondinglayer 3 may be provided only in a region on the substrate obversesurface 11 overlapping the resistor 2.

As shown in FIGS. 21 and 22, the bonding layer 3 includes the bondinglayer obverse surface 31 and the bonding layer reverse surface 32directed in opposite directions to each other. The bonding layer obversesurface 31 is directed in the same direction as the direction in whichthe substrate obverse surface 11 is directed, i.e., downward in FIG. 20.The bonding layer obverse surface 31 is in direct contact with theresistor 2. The bonding layer reverse surface 32 is in direct contactwith the substrate 1.

The insulating layer 6 is formed so as to cover the resistor 2. Theinsulating layer 6 is provided on the resistor 2 and the substrate 1 viathe bonding layer 3. The insulating layer 6 is in direct contact withthe resistor obverse surface 21 of the resistor 2. The insulating layer6 leaves uncovered portions of the resistor 2 that are spaced apart fromeach other in the first direction X1 (or the second direction X2). Theinsulating layer 6 is, for example, formed of a thermosetting material.The size of the insulating layer 6 in the third direction X3 is equal tothe size of the substrate 1 in the third direction X3. The maximumthickness (maximum size in the thickness direction Z1) of the insulatinglayer 6 is, for example, 20 to 60 μm. The insulating layer 6 is formedof a resin, for example. It is preferable to employ a material havinghigh heat conductance to form the insulating layer 6, in order tofacilitate heat generated in the resistor 2 to be dissipated to outsideof the chip resistor 200. It is preferable that the heat conductance ofthe insulating layer 6 is higher than that of the material constitutingthe substrate 1. Preferably, the heat conductance of the insulatinglayer 6 is 1.0 W/(m·K) to 5.0 W/(m·K).

The insulating layer 6 includes the insulating layer obverse surface 61,the insulating layer reverse surface 62, the insulating layer firstlateral face 63, the insulating layer second lateral face 64, theinsulating layer first end face 65, and the insulating layer second endface 66.

The insulating layer obverse surface 61 and the insulating layer reversesurface 62 are directed in opposite directions to each other. Theinsulating layer obverse surface 61 is directed in the same direction asthe direction in which the resistor obverse surface 21 is directed,i.e., downward in FIG. 20. The first electrode 4 and the secondelectrode 5 are provided on the insulating layer obverse surface 61. Apart of the insulating layer obverse surface 61, more specifically aregion of the insulating layer obverse surface 61 between the firstelectrode 4 and the second electrode 5, is exposed from the firstelectrode 4 and the second electrode 5. The insulating layer reversesurface 62 is directed in the same direction as the direction in whichthe resistor reverse surface 22 is directed, i.e., upward in FIG. 20. Inthis embodiment, the insulating layer reverse surface 62 is in directcontact with the resistor 2 and the substrate 1. Specifically, theinsulating layer reverse surface 62 is in direct contact with theresistor obverse surface 21 and the substrate obverse surface 11. Theinsulating layer first lateral face 63 is directed in the firstdirection X1. The insulating layer second lateral face 64 is directed inthe second direction X2. The insulating layer first end face 65 isdirected in the third direction X3. In this embodiment, the insulatinglayer first end face 65 is flush with the substrate first end face 15.The insulating layer second end face 66 is directed in the fourthdirection X4. The insulating layer second end face 66 is flush with thesubstrate second end face 16.

The first electrode 4 is electrically connected to the resistor 2. Thefirst electrode 4 serves to supply power to the resistor 2 from themounting substrate 893 on which the chip resistor 200 is mounted. Thefirst electrode 4 is in direct contact with the resistor 2. In thisembodiment, the first electrode 4 is in direct contact with the resistorobverse surface 21 of the resistor 2. In this embodiment, further, thefirst electrode 4 is formed so as to cover the resistor first lateralface 23 of the resistor 2 and the insulating layer 6. In thisembodiment, the insulating layer 6 is disposed between the firstelectrode 4 and the resistor 2. In this embodiment, still further, thefirst electrode 4 is not formed so as to cover the substrate reversesurface 12. However, the first electrode 4 may be formed so as to coverthe substrate reverse surface 12, unlike in this embodiment. In themounting structure 892, as shown in FIG. 20, the first electrode 4 is indirect contact with the bonding portion 895, to be electricallyconnected to a non-illustrated interconnect pattern formed on themounting substrate 893, through the bonding portion 895.

As shown in FIG. 20, the first electrode 4 includes the first underlyinglayer 41 and the first plated layer 43.

The first underlying layer 41 is in direct contact with the resistor 2.In this embodiment, the first underlying layer 41 serves as the base forforming the first plated layer 43 on the insulating layer 6 by a platingmethod. The first underlying layer 41 is in direct contact with theportion of the resistor obverse surface 21 exposed from the insulatinglayer 6. The first underlying layer 41 is formed so as to overlap theresistor 2 when viewed in the thickness direction Z1 of the substrate 1.In addition, the first underlying layer 41 includes a portion separatedfrom the resistor 2 in the thickness direction Z1. The insulating layer6 is disposed between the first underlying layer 41 and the resistor 2.The first underlying layer 41 is disposed between the first plated layer43 and the insulating layer 6. In this embodiment, it is preferable thatthe first underlying layer 41 has a large size in the first directionX1. Preferably, for example, the size of the first underlying layer 41in the first direction X1 is equal to or larger than a quarter of thesize of the resistor 2 in the first direction X1, and more preferably,equal to or larger than one third of the size of the resistor 2 in thefirst direction X1. The size of the first underlying layer 41 in thefirst direction X1 is, for example, 600 to 3200 μm. The first underlyinglayer 41 is thinner than the resistor 2. The first underlying layer 41may be formed by PVD, CVD, or printing. In this embodiment, the firstunderlying layer 41 is formed by sputtering. The thickness of the firstunderlying layer 41 is, for example, 0.5 to 1.0 nm. The first underlyinglayer 41 may contain Ni and Cr, for example. In a different embodiment,the thickness of the first underlying layer 41 may be much greater, forexample, in a range of 0.5 to 1.0 μm.

The first underlying layer 41 includes an underlying layer first lateralface 413. The underlying layer first lateral face 413 is directed in thefirst direction X1. In this embodiment, the underlying layer firstlateral face 413 is flush with the substrate first lateral face 13 andthe resistor first lateral face 23.

The first plated layer 43 is formed so as to directly cover the firstunderlying layer 41. The first plated layer 43 is provided on theresistor 2, and is in direct contact with the insulating layer 6. Thefirst plated layer 43 is in direct contact with a portion of theinsulating layer 6 that is offset in the direction X2 from the firstunderlying layer 41. In the chip resistor 200 unmounted yet on themounting substrate 893, the first plated layer 43 is outwardly exposed.Therefore, as shown in FIG. 20, in the mounting structure 892 the firstplated layer 43 is in direct contact with the bonding portion 895, thusto be electrically connected to the non-illustrated interconnect patternformed on the mounting substrate 893, through the bonding portion 895.In this embodiment, further, the first plated layer 43 is formed so asto cover the resistor first lateral face 23 of the resistor 2. Such aconfiguration is preferable because of allowing a solder fillet to beformed on the bonding portion 895.

More specifically, in this embodiment the first plated layer 43 includesa Cu layer 43 a, a Ni layer 43 b, and a Sn layer 43 c. The Cu layer 43 ais formed so as to directly cover the first underlying layer 41. The Nilayer 43 b directly covers the Cu layer 43 a. The Sn layer 43 c directlycovers the Ni layer 43 b, and is outwardly exposed. In the mountingstructure 892 of the chip resistor 200, the bonding portion 895 (in thisembodiment, solder) is bonded onto the Sn layer 43 c. For example, theCu layer 43 a has a thickness of 10 to 50 μm, the Ni layer 43 b has athickness of 1 to 10 μm, and the Sn layer 43 c has a thickness of 1 to10 μm. According to the present invention, the first plated layer 43 maynot include the Ni layer 43 b as in this embodiment.

The second electrode 5 is offset in the direction X2 from the firstelectrode 4. The second electrode 5 is electrically connected to theresistor 2. The second electrode 5 serves to supply power to theresistor 2 from the mounting substrate 893 on which the chip resistor200 is mounted. The second electrode 5 is in direct contact with theresistor 2. In this embodiment, the second electrode 5 is in directcontact with the resistor obverse surface 21 of the resistor 2. In thisembodiment, further, the second electrode 5 is formed so as to cover theresistor second lateral face 24 of the resistor 2 and the insulatinglayer 6. In this embodiment, the insulating layer 6 is disposed betweenthe second electrode 5 and the resistor 2. In this embodiment, stillfurther, the second electrode 5 is not formed so as to cover thesubstrate reverse surface 12. However, the second electrode 5 may beformed so as to cover the substrate reverse surface 12, unlike in thisembodiment. In the mounting structure 892, as shown in FIG. 20, thesecond electrode 5 is in direct contact with the bonding portion 895,thus to be electrically connected to the non-illustrated interconnectpattern formed on the mounting substrate 893, through the bondingportion 895.

As shown in FIG. 20, the second electrode 5 includes the secondunderlying layer 51 and the second plated layer 53.

The second underlying layer 51 is in direct contact with the resistor 2.In this embodiment, the second underlying layer 51 serves as the basefor forming the second plated layer 53 on the insulating layer 6 by aplating method. The second underlying layer 51 is in direct contact withthe portion of the resistor obverse surface 21 exposed from theinsulating layer 6. The insulating layer 6 is disposed between thesecond underlying layer 51 and the resistor 2. The second underlyinglayer 51 is disposed between the second plated layer 53 and theinsulating layer 6. In this embodiment, it is preferable that the secondunderlying layer 51 has a large size in the first direction X1.Preferably, for example, the size of the second underlying layer 51 inthe first direction X1 is equal to or larger than a quarter of the sizeof the resistor 2 in the first direction X1, and more preferably, equalto or larger than one third of the size of the resistor 2 in the firstdirection X1. The size of the second underlying layer 51 in the firstdirection X1 is, for example, 600 to 3200 μm. The second underlyinglayer 51 is thinner than the resistor 2. The second underlying layer 51may be formed by PVD, CVD, or printing. In this embodiment, the secondunderlying layer 51 is formed by sputtering. The thickness of the secondunderlying layer 51 is, for example, 0.5 to 1.0 nm. The secondunderlying layer 51 may contain Ni and Cr, for example. In a differentembodiment, the thickness of the second underlying layer 51 may be muchgreater, for example, in a range of 0.5 to 1.0 μm.

The second underlying layer 51 includes an underlying layer secondlateral face 514. The underlying layer second lateral face 514 isdirected in the second direction X2. In this embodiment, the underlyinglayer second lateral face 514 is flush with the substrate second lateralface 14 and the resistor second lateral face 24.

The second plated layer 53 is formed so as to directly cover the secondunderlying layer 51. The second plated layer 53 is provided on theresistor 2, and is in direct contact with the insulating layer 6. Thesecond plated layer 53 is in direct contact with a portion of theinsulating layer 6 located on the X1-side with respect to the secondunderlying layer 51. In the chip resistor 200 not mounted yet on themounting substrate 893, the second plated layer 53 is outwardly exposed.Therefore, as shown in FIG. 1, in the mounting structure 892 the secondplated layer 53 is in direct contact with the bonding portion 895, thusto be electrically connected to the non-illustrated interconnect patternformed on the mounting substrate 893, through the bonding portion 895.In this embodiment, further, the second plated layer 53 is formed so asto cover the resistor second lateral face 24 of the resistor 2. Such aconfiguration is preferable because of allowing a solder fillet to beformed on the bonding portion 895.

More specifically, in this embodiment the second plated layer 53includes a Cu layer 53 a, a Ni layer 53 b, and a Sn layer 53 c. The Culayer 53 a is formed so as to directly cover the second underlying layer51. The Ni layer 53 b directly covers the Cu layer 53 a. The Sn layer 53c directly covers the Ni layer 53 b, and is outwardly exposed. In themounting structure 892 of the chip resistor 200, the bonding portion 895(in this embodiment, solder) is bonded onto the Sn layer 53 c. Forexample, the Cu layer 53 a has a thickness of 10 to 50 μm, the Ni layer53 b has a thickness of 1 to 10 μm, and the Sn layer 53 c has athickness of 1 to 10 μm. According to the present invention, the secondplated layer 53 may not include the Ni layer 53 b as in this embodiment

A manufacturing method of the chip resistor 200 will be described below.

Referring first to FIG. 29, a substrate sheet 810 is prepared. Thesubstrate sheet 810 is the material to be formed into the substrate 1.The substrate sheet 810 is formed of an insulative material, such as aceramic or a resin, and examples of the former include Al₂O₃, AlN, andSiC. The substrate sheet 810 includes a front surface 811 and a rearsurface 812 directed in opposite directions to each other.

As shown in FIGS. 30 and 31, a bonding material 830 is adhered to thefront surface 811 of the substrate sheet 810. The bonding material 830is to be formed into the bonding layer 3. In this embodiment, thebonding material 830 is a heat-conductive adhesive sheet. In FIG. 31,the bonding material 830 is tentatively thermal-bonded to the frontsurface 811 of the substrate sheet 810.

Referring again to FIGS. 30 and 31, the resistor block 820 is bondedonto the front surface 811 via the bonding material 830. In thisembodiment, the resistor block 820 is tentatively thermal-bonded to thebonding material 830 in the state shown in FIGS. 30 and 31. The resistorblock 820 is composed of a plurality of sections, each of which is to beformed into the resistor 2. To form the serpentine-shaped resistor 2 inthis embodiment, a plurality of serpentine-shaped sections are formed byetching or punching in the resistor block 820 before the resistor block820 is bonded to the sheet front surface 811. Then the resistor block820 is trimmed (not shown) to adjust the resistance of the resistor 2.The trimming is performed, for example, with a laser, a sand blaster, adicer, or a grinder.

Instead of the adhesive sheet, a liquid adhesive may be employed as thebonding material 830 to adhere the resistor block 820 to the frontsurface 811 of the substrate sheet 810.

Proceeding to FIGS. 32 and 33, the insulating film 860 is formed. Theinsulating film 860 is the material to be formed into the insulatinglayer 6. The insulating film 860 is formed as a plurality of stripsextending in one direction, for example by printing or application. Apart of the resistor block 820 is exposed from the insulating film 860.

Proceeding to FIGS. 34 and 35, the conductive material 840 is formed onthe resistor block 820. The conductive material 840 is to be formed intothe first underlying layer 41 or the second underlying layer 51. Thedeposition of the conductive material 840 may be performed through a PVDor CVD process. In the case of forming the conductive material 840 byPVD, for example sputtering may be performed. In this embodiment, theconductive material 840 is formed in a strip shape along the insulatingfilm 860, and therefore a part of the insulating film 860 is exposedfrom the conductive material 840. To form the conductive material 840 ina strip shape, for example a masking method may be adopted. Theconductive material 840 may be formed of Ni or Cr, for example.

Proceeding to FIGS. 36 and 37, the resistor block 820 is cut into aplurality of individual pieces 886. In this embodiment, the resistorblock 820 and substrate sheet 810 are collectively cut. To obtain theindividual pieces 886, for example a punching or dicing method may beadopted. In this embodiment, punching is performed to obtain theindividual pieces 886.

The cutting process to obtain the individual pieces 886 provides thesubstrate first lateral face 13, the substrate second lateral face 14,the substrate first end face 15, the substrate second end face 16, theresistor first lateral face 23, the resistor second lateral face 24, theunderlying layer first lateral face 413, the underlying layer secondlateral face 514, the insulating layer first end face 65, and theinsulating layer second end face 66. By cutting the substrate sheet 810and the resistor block 820 at a time, the substrate first lateral face13, the resistor first lateral face 23, and the underlying layer firstlateral face 413 can be made flush with each other. Likewise, cuttingthe substrate sheet 810 and the resistor block 820 at a time makes thesubstrate second lateral face 14, the resistor second lateral face 24,and the underlying layer second lateral face 514 flush with each other.Likewise, the above cutting process makes the substrate first end face15 and the insulating layer first end face 65 flush with each other.Further, the above cutting process makes the substrate second end face16 and the insulating layer second end face 66 flush with each other.

Then the first plated layer 43 (Cu layer 43 a, Ni layer 43 b, and Snlayer 43 c) and the second plated layer 53 (Cu layer 53 a, Ni layer 53b, and Sn layer 53 c) shown in FIG. 20 are formed on each of theindividual pieces 886. To form the first plated layer 43 and the secondplated layer 53, for example a barrel plating method may be employed.Throughout the foregoing process, the chip resistor 200 can be obtained.

This embodiment provides the following advantages.

In this embodiment, the insulating layer 6 has a heat conductance ashigh as 1.0 W/(m·K) to 5.0 W/(m·K). Such a property facilitates the heatgenerated in the resistor 2 to be dissipated to outside of the chipresistor 200 through the insulating layer 6. Therefore, the chipresistor 200 can be prevented from being overheated.

In this embodiment, the first electrode 4 includes the first underlyinglayer 41 in direct contact with the resistor 2 and the first platedlayer 43 covering the first underlying layer 41. The insulating layer 6is disposed between the first underlying layer 41 and the resistor 2.The mentioned configuration facilitates the first plated layer 43 to beformed on the insulating layer 6. Therefore, the first electrode 4 canbe formed with a larger area. The increase in area of the firstelectrode 4 facilitates the heat generated in the resistor 2 to bedischarged to the mounting substrate 893 through the first electrode 4.Thus, the heat dissipation performance of the chip resistor 200 can beimproved.

In this embodiment, the substrate 1 is formed of an insulative material.In this case, there is no need to employ a Cu electrode which isrelatively thick. Accordingly, the step of processing the Cu electrodecan be skipped, and resultantly the production efficiency of the chipresistor 200 can be improved.

In this embodiment, the substrate 1 and the mounting substrate 893 areboth glass epoxy resin substrates. Accordingly, the substrate 1 and themounting substrate 893 have generally the same thermal expansioncoefficient. When the substrate 1 is thermally expanded during the useof the chip resistor 200, the mounting substrate 893 is supposed tothermally expand at the same rate. Such a configuration prevents amalfunction that may arise from the impact of thermal expansion duringthe use of the chip resistor 200, for example fracture of the chipresistor 200.

First Variation of Second Embodiment

Referring to FIG. 38, a first variation of the second embodiment of thepresent invention will be described.

FIG. 38 is a cross-sectional view showing the first variation of thesecond embodiment.

A chip resistor 201 shown in FIG. 38 is different from the chip resistor200 in that the resistor first lateral face 23 and the resistor secondlateral face 24 of the resistor 2 are covered with the insulating layer6. The remaining portions are configured in the same way as those of thechip resistor 200, and hence the description will not be repeated.

The chip resistor 201 can also provide the same advantages as thoseprovided by the chip resistor 200.

Second Variation of Second Embodiment

Referring to FIG. 39, a second variation of the second embodiment of thepresent invention will be described.

FIG. 39 is a cross-sectional view showing the second variation of thesecond embodiment.

A chip resistor 202 shown in FIG. 39 is different from the chip resistor200 in that the first plated layer 43 includes a face that is flush withthe underlying layer first lateral face 413 of the first underlyinglayer 41, and that the second plated layer 53 includes a face that isflush with the underlying layer first lateral face 514 of the secondunderlying layer 51. The remaining portions are configured in the sameway as those of the chip resistor 200, and hence the description willnot be repeated. Here, to manufacture the chip resistor 202, the platedlayer is formed in advance of the cutting process of the substrate sheet810 and the resistor block 820 described with reference to FIGS. 36 and37.

The chip resistor 202 can also provide the same advantages as thoseprovided by the chip resistor 200.

Referring now to FIG. 40 through FIG. 47, a third embodiment of thepresent invention will be described.

A chip resistor mounting structure A893 shown in FIG. 40 includes a chipresistor 300, the mounting substrate 893, and the bonding portion 895.

The mounting substrate 893 and the bonding portion 895 are configured inthe same way as those of the first embodiment, and hence the descriptionwill not be repeated in this embodiment.

The chip resistor 300 shown in FIGS. 40 and 41 includes the substrate 1,the resistor 2, the bonding layer 3, the first electrode 4, the secondelectrode 5, and a heat conducting portion 7.

The substrate 1 and the resistor 2 are configured in the same way asthose of the first embodiment, and hence the description will not berepeated in this embodiment.

The bonding layer 3 is formed so as to cover the resistor 2. The bondinglayer 3 is in direct contact with the resistor 2 and the substrate 1.Specifically, the bonding layer 3 is in direct contact with the resistorobverse surface 21 of the resistor 2 and the substrate obverse surface11 of the substrate 1. The bonding layer 3 serves to bond a firstconductive plate A11 and a second conductive plate A1 t to the substrate1 and the resistor 2. It is preferable that the bonding layer 3 isformed of an insulative material, typically exemplified by anepoxy-based material. It is preferable to employ a material having highheat conductance to form the bonding layer 3, in order to facilitateheat generated in the resistor 2 to be dissipated through the bondinglayer 3 to outside of the chip resistor 300. The heat conductance of thematerial constituting the bonding layer 3 is, for example, 0.5 W/(m·K)to 3.0 W/(m·K). The thickness (size in the thickness direction Z1) ofthe bonding layer 3 of the insulating layer 6 is, for example, 30 to 100μm. The bonding layer 3 may be formed from a sheet-shaped material or aliquid material.

The first electrode 4 is electrically connected to the resistor 2. Thefirst electrode 4 serves to supply power to the resistor 2 from themounting substrate 893 on which the chip resistor 300 is mounted. Thefirst electrode 4 is in direct contact with the resistor 2. In thisembodiment, the first electrode 4 is in contact with the resistor firstlateral face 23 of the resistor 2 and the bonding layer 3. In thisembodiment, further, the bonding layer 3 is disposed between the firstelectrode 4 and the resistor 2. In the mounting structure A893, thefirst electrode 4 is in direct contact with the bonding portion 895, tobe electrically connected to a non-illustrated interconnect patternformed on the mounting substrate 893, through the bonding portion 895.

The first electrode 4 includes a first conductive plate A11 and a firstplated layer A4.

The first conductive plate A11 has a plate-like shape and is formed of aconductive material, examples of which include Cu, Ag, Au, and Al. Theheat generated in the resistor 2 is dissipated through the firstconductive plate A11 to outside of the chip resistor 300. The thickness(size in the thickness direction Z1) of the first conductive plate A11is, for example, 200 to 800 μm.

The first conductive plate A11 includes a first conductive plate frontsurface A111, a first conductive plate rear surface A112, a firstconductive plate outer lateral face A113, a first conductive plate innerlateral face A114, a first conductive plate end face A115, and anotherfirst conductive plate end face A116. In this embodiment, at least thefirst conductive plate front surface A111, the first conductive platerear surface A112, the first conductive plate outer lateral face A113,the first conductive plate end face A115 and the first conductive plateend face A116 are flat.

The first conductive plate front surface A111 and the first conductiveplate rear surface A112 are directed in opposite directions to eachother. The first conductive plate front surface A111 is directed in onedirection of the thickness direction Z1, and the first conductive platerear surface A112 is directed in the other direction of the thicknessdirection Z1. The first conductive plate outer lateral face A113 isdirected in the first direction X1. The first conductive plate innerlateral face A114 is directed in the second direction X2. Thus, thefirst conductive plate outer lateral face A113 and the first conductiveplate inner lateral face A114 are directed in opposite directions toeach other. The first conductive plate inner lateral face A114 isdirected toward the second conductive plate A12. The first conductiveplate end face A115 is directed in the third direction X3. The firstconductive plate end face A116 is directed in the fourth direction X4.Thus, the first conductive plate end face A115 and the first conductiveplate end face A116 are directed in opposite directions to each other.

The first plated layer A4 shown in FIG. 40 is electrically connected tothe resistor 2. The first plated layer A4 is formed so as to directlycover the first conductive plate outer lateral face A113. In thisembodiment, further, the first plated layer A4 is formed so as todirectly cover the first conductive plate rear surface A112, the firstconductive plate inner lateral face A114, the first conductive plate endface A115, and the first conductive plate end face A116. However, thefirst plated layer A4 may not directly cover the first conductive platerear surface A112, the first conductive plate inner lateral face A114,the first conductive plate end face A115, and the first conductive plateend face A116, and a part of those surfaces may be exposed from thefirst plated layer A4. The first plated layer A4 is in contact with theresistor 2.

The first plated layer A4 includes a first inner plated layer A41 and afirst outer plated layer A43. The first inner plated layer A41 is formedof, for example, Cu, Ag, or Au, so as to directly cover the firstconductive plate outer lateral face A113. In this embodiment, the firstinner plated layer A41 directly covers the entirety of the firstconductive plate outer lateral face A113. In this embodiment, further,the first inner plated layer A41 directly covers the first conductiveplate rear surface A112, the first conductive plate inner lateral faceA114, the first conductive plate end face A115, and the first conductiveplate end face A116. The first outer plated layer A43 is formed on thefirst inner plated layer A41. When the chip resistor 300 is mounted,solder (conductive bonding portion 895) is applied to the first outerplated layer A43. The first outer plated layer A43 is, for example,formed of Sn.

In this embodiment, the first plated layer A4 also includes a firstintermediate plated layer A42. The first intermediate plated layer A42is disposed between the first inner plated layer A41 and the first outerplated layer A43. The first intermediate plated layer A42 is, forexample, formed of Ni. Alternatively, the first intermediate platedlayer A42 may be excluded from the first plated layer A4, so that thefirst inner plated layer A41 and the first outer plated layer A43 may bein direct contact with each other.

For example, the first inner plated layer A41 has a thickness of 10 to50 μm, the first intermediate plated layer A42 has a thickness of 1 to10 μm, and the first outer plated layer A43 has a thickness of 1 to 10μm.

The second electrode 5 is offset in the direction X2 from the firstelectrode 4. The second electrode 5 is electrically connected to theresistor 2. The second electrode 5 serves to supply power to theresistor 2 from the mounting substrate 893 on which the chip resistor300 is mounted. The second electrode 5 is in direct contact with theresistor 2. In this embodiment, the second electrode 5 is in directcontact with the resistor obverse surface 21 of the resistor 2. In thisembodiment, further, the second electrode 5 is formed so as to cover theresistor second lateral face 24 of the resistor 2 and the insulatinglayer 6. In this embodiment, the insulating layer 6 is disposed betweenthe second electrode 5 and the resistor 2. In this embodiment, stillfurther, the second electrode 5 is not formed so as to cover thesubstrate reverse surface 12. However, the second electrode 5 may beformed so as to cover the substrate reverse surface 12, unlike in thisembodiment. In the mounting structure 891, as shown in FIG. 1, thesecond electrode 5 is in direct contact with the bonding portion 895,thus to be electrically connected to the non-illustrated interconnectpattern formed on the mounting substrate 893, through the bondingportion 895.

The second electrode 5 includes a second conductive plate A12 and asecond plated layer A5.

The second conductive plate A12 is spaced apart from the firstconductive plate A11. Specifically, the second conductive plate A12 isspaced away from the first conductive plate A11 in the direction X2,opposite to the first direction X1. The second conductive plate A12 hasa plate shape and is formed of a conductive material, examples of whichinclude Cu, Ag, Au, and Al. The heat generated in the resistor 2 isdissipated through the second conductive plate A12 to outside of thechip resistor 300. The thickness (size in the thickness direction Z1) ofthe second conductive plate A12 is, for example, 200 to 800 μm.

The second conductive plate A12 includes a second conductive plate frontsurface A121, a second conductive plate rear surface A122, a secondconductive plate outer lateral face A123, a second conductive plateinner lateral face A124, a second conductive plate end face A125, andanother second conductive plate end face A126. In this embodiment, atleast the second conductive plate front surface A121, the secondconductive plate rear surface A122, the second conductive plate outerlateral face A123, the second conductive plate end face A125 and thesecond conductive plate end face A126 are flat.

The second conductive plate front surface A121 and the second conductiveplate rear surface A122 are directed in opposite directions to eachother. The second conductive plate front surface A121 is directed in onedirection of the thickness direction Z1, and the second conductive platerear surface A122 is directed in the other direction of the thicknessdirection Z1. The second conductive plate outer lateral face A123 isdirected in the first direction X1. The second conductive plate innerlateral face A124 is directed in the second direction X2. Thus, thesecond conductive plate outer lateral face A123 and the secondconductive plate inner lateral face A124 are directed in oppositedirections to each other. The second conductive plate inner lateral faceA124 is directed toward the second conductive plate A12. The secondconductive plate end face A125 is directed in the third direction X3.The second conductive plate end face A126 is directed in the fourthdirection X4. Thus, the second conductive plate end face A125 and thesecond conductive plate end face A126 are directed in oppositedirections to each other.

The second plated layer A5 is electrically connected to the resistor 2.In this embodiment, the second plated layer A5 is formed so as todirectly cover the entirety of the second conductive plate outer lateralface A123. In this embodiment, further, the second plated layer A5 isformed so as to directly cover the second conductive plate rear surfaceA122, the second conductive plate inner lateral face A124, the secondconductive plate end face A125, and the second conductive plate end faceA126. However, the second plated layer A5 may not directly cover thesecond conductive plate rear surface A122, the second conductive plateinner lateral face A124, the second conductive plate end face A125, andthe second conductive plate end face A126, and a part of those surfacesmay be exposed from the second plated layer A5.

The second plated layer A5 includes a second inner plated layer A51 anda second outer plated layer A53. The second inner plated layer A51 isformed of, for example, Cu, Ag, or Au, so as to directly cover thesecond conductive plate outer lateral face A123. In this embodiment, thesecond inner plated layer A51 directly covers the entirety of the secondconductive plate outer lateral face A123. In this embodiment, further,the second inner plated layer A51 directly covers the second conductiveplate rear surface A122, the second conductive plate inner lateral faceA124, the second conductive plate end face A125, and the secondconductive plate end face A126. The second outer plated layer A53 isformed on the second inner plated layer A51. When the chip resistor 300is mounted, solder (conductive bonding portion 895) is applied to thesecond outer plated layer A53. The second outer plated layer A53 is, forexample, formed of Sn.

In this embodiment, the second plated layer A5 also includes a secondintermediate plated layer A52. The second intermediate plated layer A52is disposed between the second inner plated layer A51 and the secondouter plated layer A53. The second intermediate plated layer A52 is, forexample, formed of Ni. Alternatively, the second intermediate platedlayer A52 may be excluded from the second plated layer A5, so that thesecond inner plated layer A51 and the second outer plated layer A53 maybe in direct contact with each other.

For example, the second inner plated layer A51 has a thickness of 10 to50 μm, the second intermediate plated layer A52 has a thickness of 1 to10 μm, and the second outer plated layer A53 has a thickness of 1 to 10μm.

The heat conducting portion 7 is insulative and disposed between thefirst conductive plate A11 and the second conductive plate A12. The heatconducting portion 7 is formed of an epoxy-based material. In thisembodiment, the heat conducting portion 7 is formed so as to directlycover the bonding layer 3, more specifically the rear face of thebonding layer 3. In addition, the heat conducting portion 7 is in directcontact with the first conductive plate inner lateral face A114 of thefirst conductive plate A11 and the second conductive plate inner lateralface A124 of the second conductive plate A12. The heat conductingportion 7 is, for example, formed of a thermosetting material. In thisembodiment, the heat conducting portion 7 is in direct contact with thefirst plated layer A4 and the second plated layer A5. To facilitate heatgenerated in the resistor 2 to be dissipated to outside of the chipresistor 300, it is preferable that the material constituting the heatconducting portion 7 has higher heat conductance than a materialconstituting the bonding layer 3. For example, the heat conductance ofthe material constituting the heat conducting portion 7 is 0.5 W/(m·K)to 3.0 W/(m·K).

A manufacturing method of the chip resistor 300 will be described below.

Referring first to FIGS. 42 to 44, a mother material A810 is prepared.FIG. 42 illustrates the front surface A811 of the mother material A810,and FIG. 43 illustrates the rear surface A812 of the mother materialA810. The mother material A810 is to be formed into the first conductiveplate A11 and the second conductive plate A12. The mother material A810is formed of a conductive material such as Cu, Ag, Au, or Al. The mothermaterial A810 includes a plurality of slits 816. The slits 816 are eachformed so as to extend in one direction and to penetrate through themother material A810 from the front surface A811 to the rear surfaceA812. The inner wall of the slit 816 corresponds to the first conductiveplate inner lateral face A114 and the second conductive plate innerlateral face A124. The slits 816 may be formed by etching or punching,for example.

As shown in FIG. 45, the front surface A811 and the composite sheet 850(composed of substrate sheet 810 and resistor block 820) are bondedtogether with the bonding material 830. The bonding material 830 is tobe formed into the bonding layer 3 as described earlier. In thisembodiment, the bonding material 830 is a heat-conductive adhesivesheet, and the resistor block 820 is tentatively thermal-bonded to thebonding material 830 in the state shown in FIG. 45.

Instead of the adhesive sheet, a liquid adhesive may be employed as thebonding material 830.

As shown in FIG. 46, a heat conductive material A870 is provided in theslits 816. The heat conductive material A870 is to be formed into theheat conducting portion 7. Though not shown, the intermediate productshown in FIG. 46 is then cured at a temperature of, for example, 150 to200° C.

As shown in FIG. 47, the intermediate product shown in FIG. 46 isdivided into a plurality of individual pieces 886. The plurality ofindividual pieces 886 may be obtained, for example, by cutting themother material A810 and the substrate sheet 810. To obtain theindividual pieces 886, for example punching or dicing is performed tocut the mother material A810.

Then the first plated layer A4 (first inner plated layer A41, firstintermediate plated layer A42, and first outer plated layer A43) and thesecond plated layer A5 (second inner plated layer A51, secondintermediate plated layer A52, and second outer plated layer A53) shownin FIG. 40 are formed on the individual pieces 886. To form the firstplated layer A4 and the second plated layer A5, for example a barrelplating method may be employed. Throughout the foregoing process, thechip resistor 300 can be obtained.

This embodiment provides the following advantages. In the aboveembodiment, the resistor 2 is embedded in the substrate 1. Such aconfiguration ensures that the overall size of the substrate 1 and theresistor 2 in the thickness direction Z1 of the substrate 1 are to bereduced. Therefore, the chip resistor 300 can be formed in a reducedthickness.

In this embodiment, the bonding layer 3 has a heat conductance as highas 0.5 W/(m·K) to 3.0 W/(m·K). Such a property facilitates the heatgenerated in the resistor 2 to be dissipated to outside of the chipresistor 300 through the bonding layer 3. Thus, the chip resistor 300can be prevented from being overheated.

In this embodiment, the heat generated in the resistor 2 can beefficiently discharged to the mounting substrate 893 through the firstconductive plate A11 and the second conductive plate A12. Such aconfiguration further assures that the overheating of the chip resistor300 can be prevented.

In this embodiment, the substrate 1 and the mounting substrate 893 areboth glass epoxy resin substrates.

Accordingly, the substrate 1 and the mounting substrate 893 havegenerally the same thermal expansion coefficient. When the substrate 1is thermally expanded during the use of the chip resistor 300, themounting substrate 893 is supposed to thermally expand at the same rate.Such a configuration prevents a malfunction that may arise from theimpact of thermal expansion during the use of the chip resistor 300, forexample fracture of the chip resistor 300.

The chip resistor 300 is illustrated schematically in FIG. 40. Actually,the cross-sectional shape of first conductive plate A11 may not be aperfect rectangular shape in the case where the punching method isemployed for cutting the mother material A810 and the substrate sheet810. For example, the cross-section of the A11 may become as shown inFIG. 48.

The first conductive plate A11 shown in FIG. 48 includes a pointedportion A119 projecting in the thickness direction Z1. The pointedportion A119 is formed at the right-hand end of the first conductiveplate A11 (that is, one end spaced apart from the other in the firstdirection X1), so as to project from the first conductive plate frontsurface A111. The first conductive plate A11 includes a first curvedsurface A118. The first curved surface A118 is formed so as to connectbetween the first conductive plate rear surface A112 and the firstconductive plate outer lateral face A113.

In the case where the punching die is set in the vertically oppositemanner, the end of the first conductive plate A11 of the chip resistormay assume a shape inverted with respect to the shape shown in FIG. 48.

As shown in FIG. 49, the pointed portion A119 is formed on a side of thefirst conductive plate rear surface A112. The first curved surface A118is formed so as to connect between the first conductive plate frontsurface A111 and the first conductive plate outer lateral face A113.

FIG. 50 illustrates a variation of the above embodiment.

In a chip resistor 301 shown in FIG. 50, the first conductive plate A11protrudes in the first direction X1 with respect to the right end faceof the resistor 2 (resistor first lateral face 23). In addition, thecurved surface A118 is offset in the first direction X1 from the rightend face of the resistor 2 (resistor first lateral face 23). Likewise,the second conductive plate A12 protrudes in the second direction X2with respect to the left end face of the resistor 2 (resistor secondlateral face 24), and the curved surface A128 is offset in the seconddirection X2 from the left end face of the resistor 2 (resistor secondlateral face 24).

A manufacturing method of the chip resistor 301 configured as above willbe described below.

The substrate sheet 810 and the resistor block 820 with the bondingmaterial 830 bonded thereto as shown in FIG. 45 is collectively cut bydicing, to form a plurality of individual pieces A886 shown in FIG. 51.A non-illustrated dicing tape is stuck to the upper face of thesubstrate sheet 810 shown in the upper section of FIG. 51, and thereforethe individual pieces A886 are prevented from falling apart.

After the heat conductive material A870 is provided in the slits 816 ofthe mother material A810 shown in FIG. 44, the portions of the mothermaterial A810 corresponding to the first conductive plate A11 and thesecond conductive plate A12 are pushed by a non-illustrated tool, sothat those portions are made to protrude with respect to the surroundingportions, as shown in the lower section of FIG. 51. At this point, theportions correspOnding to the first conductive plate A11 and the secondconductive plate A12 remain connected to the surrounding portions.

As shown in FIG. 52, the portions corresponding to the first conductiveplate A11 and the second conductive plate A12 are bonded to theindividual pieces A886 via the bonding material 830. Then the portionscorresponding to the first conductive plate A11 and the secondconductive plate A12 are separated from the surrounding portions bypunching. Upon forming thereafter the first plated layer A4 and thesecond plated layer A5, the chip resistor 301 can be obtained.

The foregoing manufacturing method eliminates the need to cut thesubstrate sheet 810 and the resistor block 820 by punching. Therefore,the end portion of the substrate sheet 810 and the resistor block 820can be prevented from being bent.

FIG. 53 illustrates another variation of the above embodiment.

A chip resistor 302 shown in FIG. 53 is different from the chip resistor300 in that a part of the resistor reverse surface 22 of the resistor 2is covered with the first plated layer A4 or the second plated layer A5.The chip resistor 302 can be obtained by dicing a part of the substrate1 (substrate sheet 810) using a dicing blade, before forming theindividual pieces 886 by punching.

The chip resistor 302 thus configured also provides the same advantagesas those provided by the chip resistor 300. The configuration accordingto this variation, in which a part of the resistor reverse surface 22 ofthe resistor 2 is covered with the first plated layer A4 or the secondplated layer A5, may be combined with the resistor 301 shown in FIG. 50.

The present invention is not limited to the foregoing embodiments.Specific configurations of the constituents of the present invention maybe modified in various manners within the scope of the presentinvention.

In the foregoing embodiments, the resistor is embedded in a substratemade of a glass epoxy resin. Alternatively, a substrate may be composedof a base plate (made of e.g. a glass epoxy resin) and an insulatinglayer formed on a surface of the base plate, and the resistor may beembedded in the insulating layer.

Configurations according to the present invention, as well as thevariations thereof, may be presented as in the following appendices.

APPENDIX 1

A chip resistor including: a resistor; an insulating layer covering theresistor; a first electrode electrically connected to the resistor; anda second electrode electrically connected to the resistor and spacedapart from the first electrode in a second direction opposite to a firstdirection. The first electrode includes an underlying layer in directcontact with the resistor and a plated layer covering the underlyinglayer, and the insulating layer is disposed between the underlying layerand the resistor.

APPENDIX 2

The chip resistor according to Appendix 1, in which the underlying layeris disposed between the plated layer and the insulating layer.

APPENDIX 3

The chip resistor according to Appendix 1 or 2, in which the underlyinglayer is at least one quarter as large as the resistor, in the firstdirection.

APPENDIX 4

The chip resistor according to Appendix 1 or 2, in which the underlyinglayer is at least one third as large as the resistor, in the firstdirection.

APPENDIX 5

The chip resistor according to any one of Appendices 1 to 4, in whichthe underlying layer has a size of 600 to 3200 μm in the firstdirection.

APPENDIX 6

The chip resistor according to any one of Appendices 1 to 5, in whichthe underlying layer is thinner than the resistor.

APPENDIX 7

The chip resistor according to any one of Appendices 1 to 6, in whichthe underlying layer has a thickness of 0.5 to 1.0 nm.

APPENDIX 8

The chip resistor according to any one of Appendices 1 to 7, in whichthe underlying layer is formed by one of PVD, CVD, and printing.

APPENDIX 9

The chip resistor according to any one of Appendices 1 to 7, in whichthe underlying layer is formed by sputtering.

APPENDIX 10

The chip resistor according to any one of Appendices 1 to 9, in whichthe underlying layer is formed of a Ni—Cr alloy.

APPENDIX 11

The chip resistor according to any one of Appendices 1 to 10, in whichthe plated layer is in direct contact with the insulating layer.

APPENDIX 12

The chip resistor according to any one of Appendices 1 to 11, in whichthe plated layer is in direct contact with a portion of the insulatinglayer located offset from the underlying layer in the second direction.

APPENDIX 13

The chip resistor according to any one of Appendices 1 to 12, in whichthe plated layer includes a Cu layer and a Sn layer, and the Cu layer isdisposed between the Sn layer and the resistor.

APPENDIX 14

The chip resistor according to Appendix 13, in which the plated layerincludes a Ni layer disposed between the Cu layer and the Sn layer.

APPENDIX 15

The chip resistor according to any one of Appendices 1 to 14, in whichthe resistor includes a resistor first lateral face directed in thefirst direction, the underlying layer includes an underlying layer firstlateral face directed in the first direction, and the resistor firstlateral face is flush with the underlying layer first lateral face.

APPENDIX 16

The chip resistor according to Appendix 15, in which the resistor firstlateral face and the underlying layer first lateral face are coveredwith the plated layer.

APPENDIX 17

The chip resistor according to any one of Appendices 1 to 16, in whichthe resistor includes a resistor reverse surface and a resistor obversesurface directed in opposite directions to each other, and the resistorreverse surface is in direct contact with the substrate.

APPENDIX 18

The chip resistor according to any one of Appendices 1 to 17, in whichthe insulating layer includes an insulating layer reverse surface and aninsulating layer obverse surface directed in opposite directions to eachother, and the insulating layer obverse surface is in direct contactwith the underlying layer.

APPENDIX 19

The chip resistor according to any one of Appendices 1 to 18, in whichthe insulating layer includes a portion disposed between the resistorand the first electrode, and a portion disposed between the resistor andthe second electrode.

APPENDIX 20

The chip resistor according to any one of Appendices 1 to 18, in whichthe first electrode and the second electrode are formed on theinsulating layer obverse surface.

APPENDIX 21

The chip resistor according to Appendix 20, in which a part of theinsulating layer obverse surface is exposed from the first electrode andthe second electrode.

APPENDIX 22

The chip resistor according to any one of Appendices 1 to 21, in whichthe insulating layer has a heat conductance of 1.0 W/(m·K) to 5.0W/(m·K).

APPENDIX 23

The chip resistor according to any one of Appendices 1 to 22, furtherincluding a substrate on which the resistor is mounted.

APPENDIX 24

The chip resistor according to Appendix 23, in which the substrate isformed of an insulative material.

APPENDIX 25

The chip resistor according to Appendix 23 or 24, in which the substrateincludes a substrate end face, the insulating layer includes aninsulating layer end face, and the substrate end face and the insulatinglayer end face are both directed in a third direction perpendicular toboth the thickness direction of the substrate and the first direction,where the two faces are flush with each other:

APPENDIX 26

The chip resistor according to any one of Appendices 1 to 25, in whichthe substrate includes a substrate reverse surface and a substrateobverse surface directed in opposite directions to each other, theresistor is located adjacent to the substrate obverse surface, and thesubstrate reverse surface is exposed.

APPENDIX 27

The chip resistor according to any one of Appendices 23 to 26, in whicha material constituting the substrate has higher heat conductance than amaterial constituting the insulating layer.

APPENDIX 28

The chip resistor according to any one of Appendices 23 to 27, furtherincluding a bonding layer disposed between the substrate and theresistor.

APPENDIX 29

The chip resistor according to Appendix 28, in which the bonding layeris formed of an epoxy-based material.

APPENDIX 30

The chip resistor according to any one of Appendices 1 to 29, in whichthe resistor has a serpentine shape.

APPENDIX 31

The chip resistor according to any one of Appendices 1 to 30, in whichthe resistor is formed of one of manganin, zeranin, a Ni—Cr alloy, aCu—Ni alloy, and a Fe—Cr alloy.

APPENDIX 32

A chip resistor mounting structure including: a chip resistor accordingto any one of Appendices 1 to 31; a mounting substrate on which the chipresistor is mounted; and an electroconductive bonding portion disposedbetween the mounting substrate and the chip resistor.

1-45. (canceled)
 46. A chip resistor comprising: an insulatingsubstrate; a resistive member supported by the insulating substrate; anelectrode held in contact with the resistive member, wherein theelectrode comprises a conductive plate including a pointed portion and acurved surface spaced apart from the pointed portion in a thicknessdirection of the electrode.
 47. The chip resistor according to claim 46,wherein the conductive plate has a front surface and a rear surface thatare spaced apart from each other in the thickness direction, the pointedportion being closer to the front surface than to the rear surface, thecurved surface being closer to the rear surface than to the frontsurface.
 48. The chip resistor according to claim 46, wherein theconductive plate has a front surface and a rear surface that are spacedapart from each other in the thickness direction, the pointed portionbeing closer to the rear surface than to the front surface, the curvedsurface being closer to the front surface than to the rear surface. 49.The chip resistor according to claim 46, wherein the conductive platehas a conductive outer lateral face that faces in a first directionperpendicular to the thickness direction, the resistive member has aresistive outer lateral face that faces in the first direction, and theconductive outer lateral face is offset ahead of the resistive outerlateral face in the first direction.
 50. The chip resistor according toclaim 46, wherein the resistive member has a resistive outer lateralface that faces in a first direction perpendicular to the thicknessdirection, and the curved surface is offset ahead of the resistive outerlateral face in the first direction.
 51. The chip resistor according toclaim 46, further comprising at least one plated layer formed on theconductive plate.
 52. The chip resistor according to claim 46, furthercomprising a conductive layer formed on the conductive plate, whereinthe conductive layer is held in contact with the resistive member. 53.The chip resistor according to claim 46, wherein the conductive platehas a conductive outer lateral face that faces in a first directionperpendicular to the thickness direction, and the pointed portion has aflat side flush with the conductive outer lateral face.
 54. The chipresistor according to claim 53, wherein the pointed portion is formedintegral with a remaining portion of the conductive plate and extendsalong a second direction perpendicular to the thickness direction andthe first direction.
 55. The chip resistor according to claim 53,wherein the pointed portion has a concave surface opposite to the flatside in the first direction.
 56. The chip resistor according to claim53, wherein the conductive plate has a flat surface perpendicular to thethickness direction, and the pointed portion protrudes beyond the flatsurface in the thickness direction.
 57. The chip resistor according toclaim 53, wherein the curved surface extends along a second directionperpendicular to the thickness direction and the first direction and hasa same curvature along the second direction.
 58. The chip resistoraccording to claim 53, further comprising a conductive layer formed onthe conductive plate, wherein the conductive layer held in contact withan entirety of the curved surface and an outer lateral face of theresistive member.
 59. The chip resistor according to claim 46, whereinthe insulating substrate contains a glass material.
 60. The chipresistor according to claim 46, wherein at least a part of the resistivemember is embedded in the insulating substrate.
 61. The chip resistoraccording to claim 46, wherein the electrode comprises a Cu plated layerheld in direct contact with the conductive plate.
 62. The chip resistoraccording to claim 61, wherein the electrode comprises a Ni plated layerand a Sn plated layer, the Ni plated layer being disposed between the Cuplated layer and the Sn plated layer.
 63. The chip resistor according toclaim 46, further comprising a sheet of insulating layer disposedbetween the resistive member and the electrode, wherein the curvedsurface of the electrode is exposed from the sheet of insulating layer.64. The chip resistor according to claim 63, wherein the sheet ofinsulating layer is smaller in thickness than each of the resistivemember and the electrode.
 65. The chip resistor according to claim 46,wherein the conductive plate has a flat outer lateral face that faces ina first direction perpendicular to the thickness direction, and the flatouter lateral face is directly connected to the curved surface.